Finned tube rolling



y 1961 w. H. LABAN 2,983,171

' FINNED TUBE ROLLING Filed D90. 31, 1958 2 Sheets-Sheet 1 F/Gj F/GZ.

ILLIAM HENRY LAB/KN W VENTOR BY W ATTORNEY WILLIAM HENRY LA AN INVENT M ATTORNEY United States Patent 1 FINNED TUBE ROLLING William Henry-Laban, West Hagley, England, assignor to Accles & Pollock Limited, Birmingham, England, a British company Filed Dec. 31, 1958, Ser. No. 784,204 Claims priority, application Great Britain Ian. 6, 1958 7 Claims. or. 80-58 This invention relates to the formation of external fins or ribs around metal tubes, by subjecting a tube to the action of forming rolls or discs to extrude or displace from the metal of the tube Wall an integral fin or rib, which may be of a helical form, three rolls or three sets of discs being, for example, spaced equidistantly around a tubular blank in rolling contact therewith, with the axes of the rolls, where the fin is to be of a helical form, at a slight angle to the axis of the tube according to the pitch or helix angle of the fin which is to be developed. The object of the invention is to provide a fin forming roll or disc of an improved and novel form which may,

with advantage, be used for the final finishing of fins which have already been partly developed, but which may be used also, if desired, for the complete formation of the fin, the improved roll or disc drawing out the fin by a purely rolling action, and serving to minimize tearing or breaking away of the fin, which is particularly liable to occur with very thin fins during the later stages of their formation.

According to the-invention means for developing an integral extruded fin around a tube, or for completing the development of apartly formed fin, including a disc or roll having at least one peripheral annular portion formed on one or 'each side face with an annular shoulder or shoulders presented radially outwards are provided. 1 L a The disc or roll may or shoulders having: annular inclined or rounded surfaces which, in use, are presented towardsa side of a partly formed fin, whilst a plurality of. discs having shouldered be positively driven, the shoulder I l annular portions, or'a roll with 'a plurality of annular portions, may be provided,opposed faces of each pair of adjacent annular portions having similarly disposed and similarly sized annular shoulders which press against the two sidesof the fin during its development and extrude the metal thereof radially. A series of annular portions Figure 3 is a sectional view on a larger scale of the shouldered annular portions of the disc assembly forming the finishing portion of the roll.

Figure 4 is a sectional view illustrating a modification. Referring to Figures 1 to 3 of the drawings, a plurality of rolls are employed, in the known manner, for the formation of an integral helical fin around a metal tube. In the arrangement shown diagrammatically in Figure 1, three rolls 1 are shown, each mounted on a driving shaft 2 and spaced at equal angular distances apart around the tube 3. The rolls are adapted to be moved radially into rolling contact with the tube, and the axes of the shafts 2 are disposed at a slight angle to the axis of the tube, according to the helix angle of the fin which is 'to be formed, so that the tube is advanced axially during the development of the fin. The rolls are similar or substantially similar and only one will therefore be described. In the construction shown the roll (see Figures 2 and 3) comprises a primary member 4 having around its periphery a series of annuli 5 of progressively increasing depth for the initial development of the fin 6 around the tube 3, in known manner, and a secondary portion, composed of discs 7, which comes into operation when the fin has reached a certain stage in its development. The primary member 4 and the discs 7 are mounted on the shaft 2 and are clamped together and fixed to the shaft by means of a nut 8 which clamps the assembly tightly against a collar 9 on the shaft, so that the whole assembly rotates with the shaft.

According to the invention, the discs 7, which have flat parallel sides, are formed at their peripheries with annular portions 10 which are narrower than the discs so as to provide between them a series of annular channels which become progressively deeper towards the last of the series, that is, in a direction away from the primary member 4. The side faces of the said annular portions 10 of some of the discs are formed with an annular stepped portion, or with a plurality of annular stepped portions, the remaining portions of the said side faces being straight and parallel. Thus, as shown more clearly in Figure 3, the outer annular part 10' of the first of the discs (considered from the left-hand side) has its one side face perfectly fiat or straight without a shouldered portion, but its opposite side face, and the opposed side face of the annulus of the second disc, is formed, near to the thicker body portion of the disc, with a narrow annular shoulder 11, the annular surface of the shoulder being fiat and inclined or bevelled, for example, at approximately an angle of 45 to the plane of the disc, to give a conical formation. The other side face of the annular part of the second disc, and the opposing side face of the annular part of the third disc are likewise formed with similarly disposed annular shoulders 12, but the sides are shaped so that they form between them a deeper annular groove to receive the fin. Theother side face of the annular portion of the third disc and the opposing face of the annular part of the next disc are each formed with two annular shoulders 13, 13', the corresponding shoulders on the two discs being immediately opposite to one another. The one pair of these opposed shoulders are disposed nearer to the outer peripheral edges of the discs than the other pair, and both pairs are less prominent than the shoulders 12. The next pair of opposed annuli faces are formed with three annular shouldered portions 14, 14', 14", the shoulders being still less prominent; whilst on the next pair of opposed disc faces there are also three shoulders 15, 15', 15", which are again less prominent than the last-named shoulders, the surfaces of the annuli being of a substantially shallow wave-like or undulatory form. The last two annuli 10, 10", of the series may, as shown, be carried by a single thick disc 7' and are of basically wedge-form, with plain opposed faces for finishing the fin. Or, the said annuli 10 ,10", may be on separate discs like the other annuli of the series.

The number of shoulders on the annuli may progressively increase on all the shouldered annuli of the series, or on successive groups of annuli.

When the fin 6 has reached a certain stage in its development, it is operated on by the positively-driven shouldered discs 7, the inclined annular surfaces of the shoulders on the faces of the annuli exerting a partly radial and partly lateral pressure on the fin, and causing the metal of the latter to be radially extruded and to become progressively deeper and thinner as it is acted upon by the following discs. Since the extruding surfaces of the shouldered portions of the annuli are inclined, the likelihood of the fin being torn or damaged during its process of development is less likely than if a direct lateral force were exerted against the fin.

If desired, the complete development of the fin may be effected by positively driven discs with annular shouldered portions, the primary member 4 being omitted. The inclination of the annular surfaces of the shoulders may be varied, as desired; or the said annular surfaces of the shoulders may be of a convex arcuate or rounded cross-sectional shape. Also, the position, size andnurnber, of annular shoulders on the side faces'of the disc annuli may be varied as found most suitable for the work'for which they are to be employed.

Instead of the shouldered and plain finishing annuli being provided on' a series of clamped-together discs, they may be formed around the. periphery of a single member 16 as shown in Figure 4, the shouldered annuli being indicated at and the plain wedge-shaped finishing annuli being indicated at 10', 10". The member 16 together with the primary member '4 are clamped tightly on the shaft 2 by a nut 8 as in the examplerepresented in Figure 2. i

I claim:

'1. Means for extrudinga fin upona tube by means of rolls, comprising a roll member having a plurality of spaced peripheral annular portions, separated by annular channels and having side faces, opposed side faces of successive pairs of said annular portions having at points radially outwards of the bottom of the intervening annular channel similarly disposed and similarly sized. annular shoulders presented radially outwards, whereby said annular shoulders act against the two sides of the fin during its development so as to extrude the metal thereof radially.

2. Means for extruding a fin upon a tube, comprising a roll member having a series of peripheral annular portions having side faces and Spaced apart by annular channels and respectively operable upon the side faces of successive portions of a fin being developed, said annular portions being provided on their opposed side faces with annular shoulders presentedradially outwards and situated at points outwards of the bottoms of, the annular channels, said shoulders on successive opposed faces of the annular portions in the series progressively becoming smaller.

3. Means for extruding a fin upon a tube, comprising a roll member having a series of peripheral annular portions spaced apart. by annular channels and respectively operable uponthe side faces of successive portions of a fin being developed, said annular portions having side faces having annular shoulders presented radially outwards and situated at points outwards of the bottoms of the annular channels, the number of said annular shoulders on the different pairs of opposed faces progressively increasing along the length of the series. a

4. Means for extrudinga fin upon a tube, comprising a roll member having a series of peripheral annular portions spaced apart by annular channels and respectively operable upon the side faces of successive portions of a fin being developed, said annular portions having side faces having annular shoulders presented radially outwards and situated at points outwards of the bottoms of the annular channels, the shoulders on different pairs of opposed side faces becoming progressively smaller and greater in number along the'length of the series.

5. A roll member for extruding ,a fin upon a tube, comprising a driving shaft, a plurality of discs clamped together and mounted on said shaft, said discs having annular. portions and body parts, said bodyparts being of greater thickness than said annular portions; whereby fin-receiving channels are formed between adjacent annular portions, said annular portions having on their opposed side faces annular shoulders of similar disposition and of similar size presented radially outwards and situated at points outwards of the bottoms of the annular channels, whereby said annular shoulders press against the two sides of a fin during its development so as to extrude the metal thereof radially.

6. Means for extruding a fin upona tube, comprising a roll member having a plurality of spaced. peripheral annular portions having side faces, at least some of said side faces having annular shoulders presented radially outwards intermediate the length of, said side face, and a second roll member having a series of finishing annuli, said shouldered annular portions being disposed adjacent to at least two finishing annuliat theend of,- said series of annuli, said finishing annuli being. ofwedge shape with plain opposed faces. I

7. A roll for extruding a fin upon, a, tube, comprising a driving shaft, a finishing roll portion having a plurality of peripheral annular portions forming channels therebetween and havingsidefaceshaving at points radially outwards of the bottoms of the channels. annular shoulders. presented radially outwards, .and a primary roll portion having annular portions for the initial development of a fin, said finishing roll portion-and primary roll portioni-being secured upon the driving shaftv axially adjacent to one another.

References Cited-in the file of this patent UNITED STATES PATENTS 23,820 Boss May 3, 1859 139,361 Black May 27, 1873 1,865,575 Locke July 5,1932 2,669,893 Hill Feb. 23, 1954 

